Using IoT to keep Mt. Washington hikers safe, predict weather

An early IoT adopter, the Mount Washington Observatory uses an ensemble of radios and sensors to monitor weather and alert hikers and observatory personnel.

Weather on Mount Washington in New Hampshire can be biblical. On one occasion, I started an early-morning April ascent with fresh snow at the base. Mid-day we stripped to our base layer of clothing when the bright sun warmed the temperature to 60°F. At the peak elevation of 6,288 feet, dark clouds closed in, the temperature dropped and the wind picked up. We ran for cover from lightning that had a very short distance to travel between the low clouds and the high peak to travel.

After hiking the mountain a half-dozen times, in all seasons and all conditions, it’s interesting to learn how the Mount Washington Weather Observatory on the peak uses IoT to update weather conditions on this frequent hiker destination.

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Mount Washington winter temperatures can range from 48°F to minus 44°F and in the summer, from 72°F to 8°F. Much of the mountain is overcast 60% of the time. Winter wind speeds often reach hurricane force and have been clocked at 140 mph. It is not uncommon for summer winds to reach 50 mph. Weather conditions change quickly, endangering unprepared hikers with hypothermia even in summer months.

The non-profit weather observatory, in operation since 1932, is chartered to collect atmospheric data, perform meteorological research and provide education. The observatory's website informs hikers of active conditions, updated every 15 minutes for each 1,000-foot interval. And the website and other communications channels provide vital information to observatory field staff, local government agencies, the U.S. Forestry Service and public safety rescue teams for assessing active conditions in order to protect the lives of crews during search and rescue operations.

Every year, a few hikers die from extreme and changing weather conditions. Most of the hiker rescues and deaths occur during the summer due to exposure when novice hikers, overconfident because of the warm summer weather, start the climb lightly dressed, without additional protective layers. Summer winds regularly blow at 40 mph, and temperatures can drop quickly to 40 degrees, resulting in a deadly windchill factor of 26°F.

IoT technology at the Mount Washington Observatory

The Mount Washington Observatory is an early adopter of IoT, beginning 13 years ago using an ensemble of radios and sensors. At the peak, sensors measure barometric pressure, temperature, wind speed, electric field and other conditions. The peak’s wind speed sensor (anemometer), a Pitot static sensor, uses the same technology as passenger airplanes. The electric field meter measures the difference in electric potential to detect the high electric field conditions that precede a lightning strike to protect observatory personnel.

A network of 28 sensors extends the observatory’s sensors and improves the accuracy of predictions. All sensor sites include a barometer and thermometer, and in some locations, wind speed sensors.   

The observatory turned to wireless communications to connect the sensor clusters and the observatory. Like all IoT systems, the engineering constraints are:

  • Power source
  • Transmission distance
  • Transmission frequency

Freewave FGR and FGR2 frequency-hopping spread-spectrum radios operating in the 902 to 928 MHz range were chosen for a few reasons. The lower frequency radio waves of the 900 MHz radios provide greater penetration through trees and other obstacles over shorter distances, though when distances increase, line-of-sight communication is necessary. This radio band does not require coordination of the spectrum with and licensing from the FCC. The spread spectrum design is necessary because there isn’t a coordinating function between with narrow band radios that also operate in this band.

Powering the sensor clusters is the most difficult problem. Solar panels and batteries remotely power the devices, a challenge because the mountain is covered in fog 60% of the year. A 25-watt solar panel supplies power. Energy is stored in a 240 amp-hour battery, about four times the energy storage of a car battery, to power the clusters through the night and long periods of overcast weather. The FGR sends a small amount of data from each cluster and limited transmission every 15 minutes, so the clusters can continue to transmit through long periods when the mountain is socked in with fog.

battery power drain Freewave

Arguably, this early example of IoT is not really one that will lead to the billions and billions of devices that researchers and hardware and software suppliers project because the clusters and radios are not cheap. Also, deployment and maintenance of large batteries are neither easy because of the terrain nor inexpensive.

Given the use case, weather forecasting and research and public safety, the Mount Washington Observatory sensor network produces an ROI. But for IoT, ROI produces stiff headwinds to progress unless the cost of devices, sensors and, most important, the cost of deployment drop significantly.

Copyright © 2017 IDG Communications, Inc.

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